Theresa May said that Sergei and Yulia Skripal had been attacked using a nerve agent developed by the Russian FederationGetty Images

Theresa May has cleared the way for a cyberattack on Russia as she challenged Vladimir Putin to explain how a powerful Russian nerve agent came to be used in an assassination attempt on British soil.

The prime minister told MPs today that the double agent Sergei Skripal, 66, and his daughter, Yulia, 33, were attacked in Salisbury last week with Novichok, a chemical weapon up to eight times more powerful than the notorious VX nerve agent. It has never knowingly been deployed, experts said.

Russia had carried out a “direct attack on our country” or had “lost control of this potentially catastrophically damaging nerve agent”, Mrs May said.

She set a deadline of midnight tomorrow for Russia to account for its actions, adding: “Should there…

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